Method of making elastic rubber transmission bands



H. W. GATT METHOD OF MAKING ELASTIC RUBBER TRANSMISSION BANDS Original Filed Au g. s, 1935 may 0-5522 Elf Patented Aug. 16, 1938 UNITED STATES OFFICE METHOD OF MAKING ELASTIC RUBBER TRANSMISSION BANDS Original application August 3, 1933, Serial No. 683,499. Divided and this application August 14, 1936, Serial No. 96,071

3 Claims.

This invention relates to elastic rubber transmission bands and to methods of making same, and is a division of my copending application Serial No. 683,499, filed August 3, 1933.

Endless elastic transmission bands have been extensively used in driving such devices as electric sweepers where the amount of power normally required is small and variation in the load is frequent. Any sudden increase in the load is compensated for by stretching and slipping of the belt. In order to provide against clinging of the belt to the pulley it has been proposed to chlorinate or otherwise harden the entire surface of the belt after it has been molded or otherwise manufactured. Such hardening treatment of the entire surface often results in the belt acquiring a glazed surface so that when slipping occurs, local heating of the belt takes place which may seriously burn the belt at one position in its circumference.

The principal objects of the present invention are to provide against localized burning of the belt.

Other objects will appear from the following description and the accompanying drawing.

In the drawing:

Fig. 1 is a drawing illustrating a step in the manufacture of a belt according to the invention, parts of the material being broken away.

Fig. 2 is a drawing illustrating another step in the manufacture of the belt, part of the apparatus being broken away.

Fig. 3 is a drawing illustrating a ring-cutting lathe and showing another step in the manufacture of the belt.

Fig. 4 is a perspective view of the finished belt.

Fig. 5 is a view partly in section showing the belt in use, parts being broken away.

Referring to the drawing, the belt comprises an endless band of resilient rubber having a pair of opposite faces H), II which have been chlorinated or otherwise treated to reduce their frictional properties, and having edges !2, l3 which are untreated so as to retain their natural frictional properties. Such belts are usually used to provide a quarter turn drive as illustrated in Fig. 5 wherein it is the driven pulley and i5 is a cone shaped drive pulley having a flange H5 at its small end. Whereas the treated face it] provides low frictional resistance so as to tend to slide on the pulley when the driven pulley is overloaded,

the raw edge l3. by contacting with the flange it, when the drive is overloaded, causes a slight creeping of the belt so that no single portion of the belt becomes dangerously overheated.

The belt conveniently may be constructed by winding 2. sheet of rubber around a mandrel IT to form a rubber tube It. A winding of fabric tape l9 may be applied to compact the rubber. The tube It is then vulcanized, the tape it removed and the tube I8 taken off the mandrel.

The finished tube l8 may then be treated to harden its surface by immersing the tube in a vessel 25 containing chlorine water 2| or other fluid adapted to react with the rubber at the surface of the tube.

After the surface has been treated the tube I8 is again placed on a mandrel 22 rotatably supported as by a driven jaw chuck 23 and a dead center 24. A knife rest 25 is provided along the mandrel to support a knife 26 by which the tube is divided into rings. each of which constitute a belt having a pair of treated faces and a pair of untreated edges such as shown in Figs. 4 and 5.

Other elements of the halogen group as bromine and iodine and other chemicals such as sulfur chloride may be used to treat the surface of the rubber. The treated surface while being somewhat hardened and having its frictional properties reduced is nevertheless elastic.

I claim:

1. The method of making an endless transmission band which comprises forming a tube of vulcanized rubber, treating the exposed surface of the tube to reduce its frictional characteristics, and dividing the tube circumferentially to provide belts each having at least one untreated edge.

2. The method of making an endless transmission band which comprises forming a tube of vulcanized rubber, treating the exposed surface of the tube with a member of the halogen group to reduce its frictional characteristics, and dividing the tube circumferentially to provide belts each having at least one untreated edge.

3. The method of making an endless transmission band which comprises forming a tube of vulcanized rubber, treating the exposed surface of the tube with chlorine to reduce its frictional characteristics, and dividing the tube circumferentially to provide belts each having at least one untreated edge.

HAROLD W. CATT. 

